Here are the main facts from the catalog:
Size: 84x89.5mm = quite big Weight: 570g = quite fat Optics: 13 elements in 11 groups Closest focus distance/max.magnification: 0.3m / 1:8 (I'll test this!) Filter-thread = 77mm (=standard) No IS = not so important AF does not work on D40/x-bodies , manual-focus override by pulling the focus ring back Covers APS-C-sensors or Four/thirds
Comes with a petal-shaped lens-shade but no lens-bag Price: around 440€ = second cheapest of the test-group (cheapest is the Tamron 11-18mm)

Here are my first impressions and observations from working with the lens:
The switch-over between AF and MF (by pulling the focus-ring) is not state of the art, but works quite well and intuitively while looking through the viewfinder: as soon as you notice that the focus-ring doesn’t give way to your manual focusing efforts, you remember to pull. AF is a little noisy and slow, but that’s ok with me. In low-light the focus normally finds the target, albeit that needs some "thinking" from time to time. Focus quality will be judged later. The focus-ring doesn't turn with AF, that's good The lens is much easier to get your hands around than the Sigma 12-24mm. The rubberized rings feel good.
The lens has no dof-marker. ---
You can see pictures taken for the test here. It will be slowly filling up over time. I'll also be placing "mishaps" to give you a feeling of the "hit-rate" of the lens/body-combo in automatic...

Do you mean that you have experienced problems with your exemplar, or that ALL the first exemplars produced had this problem, and so Sigma have produced a "corrected second copy" ?
(sorry but my english is not that good and i have difficulties in understanding )

Skelter, welcome to the club! My english is also not the best! That's probably the reason for the confusion around "second copy" Btw. where are you from?
I'm simply referring to the two exemplars/copies of this lens that I got in my hands/n my camera. The first was bad (and consequently sent back) and the second good (and I kept it). There were many complaints in user-forums about unstable quality from Sigma of this lens, but you could also be lucky with earlier exemplars/copies. So you could not come to the conclusion that all older Sigma 10-20mm exemplars were bad and unfortunately also not that all newer copies are good.
My personal opinion is that Sigma made a good design with the 10-20mm but f*cked it up with sloppy quality control (QC) in the early days. And I hope/assume that the many returns made them look into their QC-procedures to improve the rate of good lenses now.
But nonetheless, I would test the lens carefully when you buy one!

There is a very easy test to find out whether the lens is decentered if you have some fine structures in the shop or in front of it's door (antennae on a roof, trees, distant brick-walls.
Important is to set the lens wide open (aperture prio at f4) and disable AF (at least after the first shot) so that the conditions are equal under which you shoot 2 or 4 shots. =VERY IMPORTANTIf you're in a hurry just test the shortest focal length (i.e. 10mm) as it is the most critical, if you want to be absolutely sure, make two sets of shots at 10mm and 20mm.
Then put the fine structure into each corner of your viewfinder and pull the trigger. You'll get 4 shots of the same subject in the different corners (which are most critical with respect to sharpness) and can then compare the sharpness of these structures in-camera by zooming in on each.
When you hsoot against the sky, don't get distracted by strong background light eating into your structures and making them look "ghosty", just concentrate on the sharpness.

Perhaps it's best to try this procedure before with one of your existing lenses...

I personally love twigs from trees against the sky as test-subjects and can do with just two shots: One in normal position, and one with the camera upside down and the same crop. Thus the subjects in the picture change their position 180° and can be compared accordingly. But I think this method is best when you compare the shots on your computer with one pic turned 180°.